I want a wireless remote for the 400d that will allow me to take long bulb exposures, but i want to know if any of the canon ones have a button lock, that will hold the shutter button on the remote down, so that I wont have to hold it myself for 10 mins each time i do a 10 min exposure?
I have the RC-1 remote. About €30 in any camera shop. Its very easy to do what you want. Goto the menu and turn on these custom functions – mirror lockup and long exposure noise reduction (if necessary). Stick the camera on manual – M, then turn the dial until the camera says BULB and adjust adjust the aperture. Now all you need to do is turn the remote on (there are two on positions). Press the button once to open the shutter. Pressing it again will close the shutter. The number of minutes / seconds displays on the LCD at the back of the camera.
This is a 10 minute exposure I took using the above method. Before you ask, it was taken at night.
The hardest thing you will find is focusing in the dark.